Lightning arrester



Aug. 23, 1932. J, R, MCFARLlN LmHTNING ARRESTER Filed Aug. 31

Patented Aug. 23, 1932 UNITEDSTATES PATENT ori-*lcs JOHN ROBERT ECFARLIN, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO ELECTRIC SERVICE SUPPLIES COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORA- TION OF PENNSYLVANIA LIGHTNING ARRSTER I Application filed-.August 31, 1923.y Serial N'o. 666,299.

My invention is a lightning arrester adapted for protecting electrical apparatus from lightning and other high voltage disturb-y dynamic or line currentto ground following a discharge of high voltage current.

My improvements are particularly applicable to arrestershavinga discharge path for high voltage charges containing an impediment, such as one or more air gaps',suti cient to prevent the normal flow of dynamic or power current therethrough,y but through which such dynamic or power current will continue flowing across the arc formed by the discharge of abnormal voltages. By my improvements, the line current (which maintains the arc after the discharge of the abnormal charge or current) is short circuited to extinguish the arc'by the closing of a normally open path, which is automatically reopened as soon as the arc has been extinguished, and the ow of line current to ground is thereby interrupted. The closing of the normally open path is effected under control of current flowing in one of the several parallel conductors into which the discharge path is divided over a portion of its length, and the continuit of such dischargeV path, conductors is not a ected by the diver'- sion of the current therefrom.

In the preferred embodiment of my invention, the discharge path contains a plurality of spaced electrodes forming an air ygap or gaps; an electrodel on the one side of a gap having connected therewith a shunt resistor and a coil connected across the ends of the resistor. may be connected to ground either directly or through a series resistor. The discharge i path on the line side oft-he gap is connected with an electrode forming part of a' normally open path, which is momentarily closed by an armature actuated by current owing in the coil and when so closed forms a path to ground across the air gap, shunt resistor and The shunt resistor and coil` coil, the current liowingthereto being thus shortcircuited and the armature allowedto move-out of contactwith its coacting electrode to interrupt the discharge of the line current. n

vWhile the'escaping line current is preferably short circuited from the line side of the' gap to effect the extinguishment thereof, andthe apparatus for effecting such shortcircuitin is preferably disposed on the ground side of the gap, it is to be understood that changesmay be madev in the relative arrangement of the part-s without departing from my invention.

Such apparatus may be advantageously enveloped in a completely enclosed case by which it is protected from weather or tampering, the parts being so formedand arranged asv to require no adjustment and very little re lacement. n

The ollowing description and the accompanying drawing illustrate preferred embodiments of my invention, the characteristic features thereof being defined by the appended claims. In thedrawing, Fig. 1 is a vertical sectional View of a lightning arrester embodying my invention; Fig. 2 is a top plan view thereof, y i

partly in section; Fig. 3 is a diagrammatic illustration of the electrical paths formed by the parts; and Fig. 4 is al diagrammatic illustration of a modified form of apparatus embodying my invention. y

yAs illustrated in Figs. l, 2 and 3 of the drawing, a hollow bodyl, having an integral wall and bottom, is provided with a cover 2 adapted to be secured in place by the bayonet joints 3, the joint between the cover and body being sealed by cement. The casing thus formed is preferably made of glazed porcelain; the body being provided with the exterior lugs 4 and spaced ribs 5 for the engagement of a strap iron hanger 6.

A supporting conducting plate 7 engaged between the body and cover of the casing, is connected through the terminal 8 with aconductor 9 leadin from a line wire or device to be protected. n electrode 10 has a threaded boss 11 projecting through an aperturey in the plate`7, the electrode being held in firm enn o il gagement with the plate by a nut 12 on the boss. A non-conducting tube 13 is sleeved on the electrode and pinned thereto by a rivet 14.

The plate 7 has projecting therefrom spring clips 7 which engage the inner surface of the body 1 and serve to retain the plate 7 in fixed relation thereto. In contact with the plate 7 is a gap electrode 1 5 supported on the spool 16 and comprising a dished disc forming an annular rib 15. A second gap electrode 17, comprising a dished disc forming an annular rib 17 is spaced and insulated from the electrode 15 by the insulating` spool or collar 16 surroundingthe upper @ad Of the tube 13, the ribs l5 and 17 having between them an air gap 1S constituting` a bar to the passage of line current excepting when an arc across the gap has been formed by a high voltage discharge.

The ,gap electrode 17 is supported upon the non-conducting end of a bobbin 19 on the tube 13, on which is wound solenoid coil 2O connected with the gap electrode 17'. The bobbin 19 is supported on the tnbe 13 by friction and by a tube 21 sleeved on the. lower end thereof and pinned thereto by a rivet 22 passing through both tubes and through a bottom closure or plugr Q3.

A conduct-ing bracket- 24, clamped to the tube 2l by the clips 25, has riveted thereto the conducting sockets 126"l and 27'; The socket 26 has a shunt resistor 28 secured therein by adjustment of the screw 26a', and the socket 27has a series resistor Q7 secured therein by the adjustment of the screw 27a. The shunt resistor 25 has secured to the bottom thereof' a conducting` band 2G provided with an adjusting screw 25h, and this band is connected' by an insulated conductor 28 with the gap electrode 17 .y The end ofV the solenoid coil is connected with the bracket by means ot a screw so that the. solenoid coil terms a shunt conductor to a portion of the discharge path across the terminals of the resistor 26.

The series resistor 27 has a conducti band 27" lined upon the bottom thereof by the adjust' t fr screw 272) and such band is connected with ground wire 2 9 through tae connector 30 and ground binding post members 30" and 30. The series resistor 27 serves to limit any flow ot dynamic current to ground to a. sate and moderate value;but on low voltage circuits? such for example as those of 350 volts and under, the series resistor 27 may be omittet1 since the resistance in the ground connection, which may average about ohr-.1sr` will limit the dynamic current to a sagte value.

A conducting; armature 31 in the tube 1 3 has connected therewith a bindingor post 32 projecti y through the axial slot. in the tube. the bindingl post 32 being connected by a fieiiible conductor Bil with the bracket 251V through the screw 25". The armature rod 31 is normally held by gravity at the bottom of the tube 13 so to maintain normally open the conducting path formed when this armature is elevated into engagement with the tube electrode 10.

In operation, a lightning discharge from line to ground enters the arrester through the lead line 9, passes through the plate 7 and electrode 1.5,ju1nps the air gap 18 .forme-d between the ribs 15 and 17', and flows to ground through the connector 28, shunt resister 26, bracket 2l, se ies resistor 27, connector 3.0, ground binding post members 30 and 30 and grount conductor 29. This discharge path, containing only a small air gap and low noninductive re tors, is highly etlicient in discharging lightning. The lightning discharge does not flow through the l lv inductive solenoid windl g Q0 but through the non-inductive resistor 2G, le the higher ohmic resistance of the re ,or 2G as compared with the winding- 20 causes the dynamic or power current ol- 'lhe ioni'retion by a lightning,- discharge of the air ii ic gap 18 permits the dynamic or line current to maintain the arc between the electrode ribs 15' and' 17' and follow the disruptive charge. Since, however, the shunt resistor 26 diverts this dynamic cr line current through the solenoid coil 20, the latter attracts the armatme 31 and elcvates it into contact with the tube electrode 10. The line current is thereby diverted 'from the plate 7 through the electrode 10, armature 31, binding post 32.', conductor 34, bracket 2l, series esistor 2,7, connector 30, ground iindinp; post menjibers 30 and 30 and conductor 29 to groundl` tljiereby short circui'ting and extinguishing the arc in the gap 18 and short cir- `n0f and rendering;r inoperative the solenoid coil Q0. The short circuitingA of the solenoid coil 2O causes the `iall of' the armature 31 and' breaks the circuit therethrough. Any arci'ng from the. break takes place within the. insulatingr tube 13 between the tube electrode 10 and armature 31 instead of between the gap, electrodes, whereby the neces sity for renewal of the gap elements or adjustment of the gap due to burning is practically eliminated.

l't will be observed that the action is extremely simple, entirely automatic and positive and, as the lightning discharge itself does not at any time flow through the circuit breaker, the.. lightning discharge path, to ground is fixed and Lminterrupted. Neither the circuit breaker itself nor the position of the movable armature during operation has any etlect whatever on the elii'cicncy of thc arrester in dischargingl lightning, single charges or multiple charges of any frequency lowing :be c ischargge to ground to llow largel rhro 1li the windinugf 20, the continuity of" ground, but any member throughwhich current flows on its way from the coil, resistors or armature to ground. f

In the modification illustrated Fig. 4, the

p air gaps providing the impediment to normal discharge of dynamic current are interposed between the electromagnetic coil and series resistor (instead of between the line and the coil) and the coil and shunt resistor are connected with the line wire or other device to be protected. The parts may otherwise be similar to the parts shown in detail in the other igures. In the operation of this construction, a lightning dischare entering the arrester through the lead in wire, passes through the plate 7a, conductor 28a, shunt resistor 26a, bracket 24a, to gap electrode 15a, from the annular rib of which it leaps across the gap 18a to the annular rib of electrode 17 a, thence through the electrode 156 (contacting with the electrode 17a), across the air gap 186 to the electrode 176, and through series resistor 27a and conductor 30a to ground. The arcs formed across the air gaps by the disruptive discharge complete a path for the flow of dynamic or line current to ground. Such current is, however, diverted by the shunt resistor 26a through the electromagnetic coil 20a, connected with electrode 7a, and thereby causes the attraction of the conducting armature 31a which iselevated into contact with the electrode 10a, (electrically connected with plate 7a). As the armature is connected through the conductor 34a with electrode 17 6, the engagement of the armature with the electrode 10a short-circuits the coil 20a and gaps 18a and 186, thereby de-energizing the coil, extinguishing the arcs across gaps 18a and 186, causing the armature to ldrop and ending the iow to ground of dynamic current.

Having described my invention, I claimt 1. A protective device comprising a conductor, a non-conducting tube containing an electrode connected with said conductor,

spaced electrodes forming a spark gap, a

resistor and a coil connected in parallel and to one of said spark gap electrodes, and an armature movable in said tube into contact with the electrode therein under control of current in said coil, said armature automatically disengaging from said electrode when there is no flow of current in said coil.

2. A protective device comprising a su portin conducting plate, an insulating tu depen ing from said late, an electrode in said tube `connected with said plate, spaced electrodes forming a spark gap, a solenoid coil sleeved on said tube and connected with one of said electrodes, a resistor supported by said tube and connected with said last named electrode in parallel with said coil, and an armature reciprocable in said tube under control of current flowing in said coil.

3. A protective device comprising a hollow casing, a conducting plate supported in the upper part of said casing, an insulating tube depending from said plate and having therein an electrode connected with said plate, spaced electrodes around said tube and forming an air gap, a coil around said tube and connected with one of said ga electrodes, a resistor supported by said tu e and connected with one of said gap electrodes, andan armature movable in said tube under control of current flowing through said coil to engage and disengage said tube electrode.

In testimony whereof I have hereunto set my hand, this 29th day of August, 1923.

- JOHN ROBERT MCFARLIN. 

